This invention relates to an artificial airway device designed to facilitate lung ventilation and the insertion of endotracheal tubes or related medical instruments into the laryngeal opening of an unconscious patient, and more specifically to a laryngeal mask designed to be placed within the oropharynx region over the laryngeal opening to conceal the circumference of the laryngeal opening against the aspiration of regurgitated gastric content and provide a direct pathway from a perimeter exterior to the oral cavity to the laryngeal opening.
In general, laryngeal masks allowing for both rapid lung ventilation and the insertion of medical instruments and tubes into the laryngeal openings of patients have been described in patents such as U.S. Pat. No. 4,509,514 to Brain. Consisting of two essential parts, a breathing tube and an inflatable mask, these devices are inserted blindly into a patient's throat, and when properly positioned, terminate at the laryngeal opening. Generally, a seal is then formed around the circumference of the laryngeal opening by the inflation of a ring-like structure located on the front of the mask. Inflation of the ring exerts pressure against both the front and rear portions of the oropharynx, securing the device in place such that the laryngeal opening is positioned within the cavity in the mask face. Extending from a point external to the oral cavity, the flexible breathing tube terminates within the cavity, which is aligned axially with the laryngeal opening. The positioning of the flexible breathing tube allows the passage of small diameter endotracheal tubes or related medical instruments into the laryngeal opening, in addition to allowing for lung ventilation.
Current laryngeal masks have several drawbacks in the area of placement, lung ventilation, and endotracheal intubation. For example, during insertion and positioning, the flexible nature of the deflated ring structure and surrounding mask allows the distal end of the mask to bend back on itself, making placement difficult. Also, once installed, the current mask designs fail to exert sufficient pressure against the larynx necessary to maintain proper positioning during intubation and ventilation. This is due to the variations in the anatomy of the oropharynx region and the curvature of the device itself. Further, during lung ventilation it is possible for the tip of the epiglottis to become lodged in the distal lumen of the flexible breathing tube, which inhibits the passage of air or endo-tracheal tubes through the tube. This problem is often overcome by the placement of a series of band structures at the entrance of the distal lumen that prevent the epiglottis from entering the breathing tube. However, these band structures severely restrict the size of the endo-tracheal tubes or related medical devices that may be passed through the flexible breathing tube. Moreover, after insertion of an endo-tracheal tube or related medical device, it becomes difficult to remove the laryngeal mask from the patient's oropharynx without dislodging or accidentally extracting the endo-tracheal tube or medical device along with the laryngeal mask.
Accordingly a laryngeal mask that provides generally the same function as described above is needed that allows a more secure insertion and airtight placement, allows the unrestricted passage of large diameter endo-tracheal tubes directly into the laryngeal opening, and provides alternative airways.